Structure and autoregulation of the c-rel promoter.
Precise regulation of proto-oncogene expression appears to be essential for the proper growth and development of multi-cellular organisms. One aspect of this regulation is at the level of transcription from the proto-oncogene promoter(s). In order to characterize the promoter for the chicken c-rel proto-oncogene, we have isolated and sequenced genomic DNA containing the first exon of the chicken c-rel proto-oncogene. The c-rel promoter is structurally similar to the promoters of the so-called house-keeping genes, lacking the CAATT and TATA elements found in some cellular genes, but containing a G/C-rich box near the transcription start sites. There are multiple transcription start sites for the c-rel mRNA, which map near putative binding sites for the transcription factors HIP-1 and NF-kB. The c-rel promoter was functionally characterized by its ability to support expression of the firefly luciferase gene. The c-rel promoter is a relatively weak promoter, 100-times less active than the promoter within the spleen necrosis virus long terminal repeat (LTR). We have defined the c-rel promoter by analysis of a series of 5' deletion mutants of the c-rel promoter fused to the firefly luciferase gene. A DNA fragment containing 97 bp of 5' flanking sequence and 72 bp of 3' flanking sequence is sufficient for c-rel promoter function. Co-transfection of the c-rel promoter with a retroviral vector expressing the c-rel protein resulted in a decrease in expression from the minimal c-rel promoter. These results indicate that expression of the c-rel proto-oncogene is tightly regulated both at the level of basal promoter activity and by autoregulation of transcription by the c-rel protein.
Hannink
M
M
McArdle Laboratory for Cancer Research, University of Wisconsin, Madison 53706.
Temin
H M
HM
D000225:Adenine / Q000032:analysis; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D003596:Cytosine / Q000032:analysis; D004247:DNA / Q000032:analysis / Q000235:genetics; D005091:Exons; D006147:Guanine / Q000032:analysis; D006706:Homeostasis / Q000502:physiology*; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000502:physiology; D020569:Proto-Oncogene Proteins c-rel; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013941:Thymine / Q000032:analysis; D014158:Transcription, Genetic
D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; D012333:RNA, Messenger; D006147:Guanine; D003596:Cytosine; D004247:DNA; D008156:Luciferases; D000225:Adenine; D013941:Thymine